snip:Vertical transfer is so 20th centuryWe’ve heard of the tree of life, in which one organism begets another, passing on its genes in a vertical fashion, with this vertical transfer of genes producing a tree, with each new production becoming a new branch. The method of gene transfer that would produce a genuine circle, or ring, is horizontal transfer, in which two organisms fuse genomes to produce a new organism. The ends of the branches in this scenario fuse together via their genomes to close the circle. It is this fusion of two genomes that may have produced the eukaryotes.

Here, have some genesEukaryotes are cells with true nuclei, like the cells of our bodies. The simplest eukaryotes are the single-celled variety, like yeasts. Before eukaryotes arose, single-celled organisms without nuclei—called prokaryotes—ruled the Earth. We lumped them together in a single kingdom until comparatively recently, when taxonomists broke them into two separate domains, the Archaebacteria and the Eubacteria, with the eukaryotes making up a third. Archaebacteria are prokaryotes with a penchant for difficult living conditions, such as boiling-hot water. Eubacteria include today’s familiar representatives, Escherichia coli.

Genomic fusionAccording to the findings of Lake and Rivera, the two prokaryotic domains may have fused genomes to produce the first representatives of the Eukarya domain. By analyzing complex algorithms of genomic relationships among 30 organisms—hailing from each of the three domains—Lake and Rivera produced various family “trees” of life on Earth, and found that the “trees” with the highest cumulative probabilities of having actually occurred really joined in a ring, or a fusion of two prokaryotic branches to form the eukaryotes.